When gear shifts become noticeably rough or delayed, the causes can vary and are often expected to potentially serious. However, as German parts specialist, MEYLE, explains in a new bulletin, the potential solution is often a change of automatic transmission oil.

MEYLE experts say that some vehicle manufacturers continue to promote so-called "lifetime fills" and terms like "maintenance-free." What many drivers are not aware of I that there is no such thing as truly maintenance-free components in a vehicle. Any part expected to function reliably over the long term requires regular, professional servicing and that includes the automatic transmission oil. It performs several vital functions, which can diminish over time if not properly maintained.

Merely checking the fluid level or inspecting for leaks, is not sufficient. As transmission fluid ages, its viscosity deteriorates and the additives it contains become depleted. As a result, the oil can no longer fulfill its intended functions. Importantly, this degradation is not apparent from the fluid level alone.

Transmission systems with wet clutches, in particular, require regular oil changes. In these systems, clutch components are immersed in the transmission fluid, which can lead to the accumulation of friction material and other contaminants. Although the hydraulic filter is designed to capture such debris, its effectiveness is limited over time. Once the filter begins to clog, it may impact surrounding components such as tooth flanks and running surfaces of the gears.

At this stage, an oil change, or even a complete flush, becomes essential to prevent mechanical damage. MEYLE recommends that technicians perform a transmission oil change every 80,000 to 120,000 kilometres. MEYLE also stress that electric vehicles also require oil changes, contrary to popular belief. Even in EVs, certain components rely on lubrication to prevent premature wear and avoid costly repairs.

For more detailed information MEYLE offers a comprehensive white paper on transmission oil maintenance covering the fundamentals, relevant regulations, and expert insights. Oil changes for automatic transmissions can be downloaded here. 

Additionally, the MEYLE YouTube channel offers a dedicated playlist with helpful tips, practical advice, and step-by-step instructions:  Playlist: Automatic Transmission Oil Change